1. Field of the Invention
The present invention relates to a hard disk drive(HDD), and more particularly relates to a latching apparatus of an HDD using a bimetal in which a magnetic disk is prevented from being damaged by external vibration or impact by firmly fixing an actuator in a state where the magnetic head is being parked, using expansion and shrinkage of bimetal.
2. Description of the Related Art
Generally, computers equip an auxiliary memory as a subsidiary means of a main memory for recording much data which exceeds memory capacity of the main memory. A magnetic disk, a magnetic tape, a magnetic drum, a floppy disk and an optical disk are known as auxiliary memories. A hard disk drive having at least one magnetic disk is widely used as an auxiliary memory in a personal computer.
A conventional embodiment of the magnetic disk drive will be described hereinafter with reference to the attached drawings.
As shown in FIGS. 1 and 2, at least one magnetic disk 2 is rotatably fixed by a spindle motor(not shown) in a main body 1. Both sides of the magnetic disk 2 can memorize or read information.
An actuator is installed on one edge portion in the main body 1. The actuator includes: an arm 4 which is rotatably supported by a pivot bearing 3; a suspension 5 which is combined with and fixed to an end portion of the arm 4 in parallel with the magnetic disk 2; a pair of magnetic heads 6 which is supported by the end portion of the suspension 5 for facing each other; and a voice coil motor 7 which consists of a coil and a magnet and is installed on the arm 3.
When a pair of magnetic heads 6 access each side of the magnetic disk 2, the pivot bearing 3 is a rotational center of rotational movement of the actuator and the rotational power is generated by the voice coil motor 7.
A slider which is raising by the rotational power of the magnetic disk 2 and magnetic circuits which can memorize or read information in the magnetic disk 2 are formed as a single body in the magnetic head 6.
Moreover, when main power of the hard disk drive is turned off, as set by a system, an actuator locking apparatus automatically moves the magnetic head 6 into a parking zone in the magnetic disk 2 and prevents shaking of the actuator by external vibration or impact. For example, an automatic locking magnet 8 is attached to one edge portion of the main body 1, an automatic locking arm 9 is fixed to an end portion of the arm 4 and a latch pin 10 is fixed to the automatic locking arm 9.
As above-mentioned, in the hard disk drive generally used, when the power is turned off, the magnetic disk 2 keeps at a stop state because the spindle motor is not driven. Accordingly, the magnetic head 6 loses rising power and is in the parking zone in the magnetic disk 2 by the inputted signal in the system.
Then, the latch pin 10 of the actuator is fixed to the automatic locking magnet 8 by the strong magnetic force, the shaking of the actuator by the external vibration or impact is prevented. Consequently, the magnetic head 6 cannot intrude into a data zone of the magnetic disk 2.
In the meantime, when the power of the hard disk drive is turned on, the spindle motor rotates and the magnetic disk 2 connected to the spindle motor rotates. Consequently, the magnetic head 6 rises to a predetermined height according to the rotational pneumatic pressure of the magnetic disk 2. The raised magnetic head 6 moves from inside to outside the magnetic disk 2 and memorizes or reads data by the driving of the actuator according to a system signal.
Then, when the driving power of the voice coil motor 7 exceeds the magnetic force of the automatic locking magnet 8 which restricts the latch pin 10 in the turning off the hard disk drive, the locking state is released. Accordingly, the data is memorized or read by current strength flown in the voice coil motor 7 by moving the magnetic head 6 to a desired position.
But, in the generally used hard disk drive as above-mentioned, the magnetic force of the automatic locking magnet 8 is determined within the range which is not affected by precise position control in case that the magnetic head 6 seeks and follows a predetermined track in the magnetic disk 2. Accordingly, the magnetic force is determined by the driving power and control of the voice coil motor 7.
Consequently, locking force of the actuator has a predetermined value because magnetic force of the automatic locking magnet 8 is limited to some extent. Therefore, if an external vibration or impact is higher than the magnet force of the automatic locking magnet 8, the magnet head 6 reaches the data zone of the magnet disk 2, to thereby cause a hard defect to the data zone of the magnetic disk 2. As a result, the data memorized on the magnetic disk 2 is damaged.